Metalworking fluids are employed in metalworking operations such as cutting, forming, stamping and rolling to provide cooling and lubrication to both the workpiece and the metalworking apparatus. The metalworking fluids also function to flush away oil and debris from the worksite, and they provide corrosion protection to both the workpiece and the metalworking apparatus. Initially, metalworking fluids comprised oil-based materials or emulsions of water and oil. However, the industry has increasingly sought to replace oil-based products with water-based materials. Therefore, the industry is turning toward the use of water-based metalworking fluids.
In addition to providing a cooling function, water-based metalworking fluids must provide good lubricity to the workpiece and metalworking apparatus, and be capable of sequestering and removing debris and contaminants, including oils, from the worksite. In addition, water-based metalworking fluids should provide good corrosion protection to both equipment and workpieces. Toward that end, the industry has developed various water-based metalworking fluid compositions; however, a number of problems have arisen in connection with the use of such compositions.
Many metal alloys, particularly brass and steel alloys, include lead therein, and it has been found that this lead can react with fatty acids in a metalworking fluid to produce a water-insoluble metal soap deposit which accumulates on the metalworking apparatus. The soap scum attracts and binds any oils which may be present thereby rendering the scum very sticky. The scum is very difficult to remove from parts and machinery, and can cause binding of the metalworking machinery or otherwise interfere with the metalworking process. Therefore, there is a need for a metalworking fluid which is free of fatty acids. It has also been found that various water-based metalworking fluids include ingredients which are corrosive or otherwise reactive with copper, lead, zinc and aluminum; therefore, there is a further need for a metalworking fluid which is non-corrosive to a wide variety of metals.
Biocontamination is a significant problem in metalworking fluids. Such infection can contaminate both the metalworking fluid and the metalworking apparatus, and is a result of the growth of bacteria and/or fungal organisms in the fluid. The problem is particularly severe in water-based fluids, and there is a need for a water-based metalworking fluid which is resistant to the growth of a broad spectrum of biological species therein. In order to address the various problems discussed hereinabove, prior art metalworking fluid compositions often include phenols, cresols, halogenated materials and the like in their formulations. Many of these materials are classified as hazardous materials, and their use is restricted or severely limited by law. Therefore, it is further desirable to have a metalworking fluid which does not include any hazardous materials.
As will be described hereinbelow, the present invention is directed to a water-based metalworking fluid which provides very good lubricity and cooling to equipment and workpieces. The metalworking fluid of the present invention is compatible with, and non-corrosive toward, a wide variety of metal alloys. It is free of fatty acids and hazardous materials. The metalworking fluid of the present invention is capable of removing oils, dirt and debris from workpieces and equipment. It is resistant to biological contamination, stable and recyclable.